Systems and methods for treating a vessel using focused force

ABSTRACT

A device for introduction into a body vessel includes a main elongated element, a balloon positioned at the main elongated element distal end, a distal connecting element positioned at the distal end of the balloon to receive a guidewire during use, and a longitudinally movable sheath positioned external to the main elongated element, a position of the sheath distal end with respect to the balloon defining an exposed portion of the balloon that expands when fluid is delivered to the balloon through the inflation lumen.

CROSS REFERENCES TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. patent applicationSer. No. 11/746,682, filed May 10, 2007, which is a continuation-in-partof U.S. patent application Ser. No. 11/431,918, filed May 11, 2006, andwhich claims a priority benefit from International Patent ApplicationNo. PCT/IL2006/001150, filed Oct. 3, 2006, each of which aforementionedapplication is incorporated by reference in its entirety into thisapplication.

FIELD OF THE INVENTION

The present invention relates to a rapid exchange balloon cathetersystem having an adjustable balloon length.

BACKGROUND OF THE INVENTION

Balloon dilatation catheters are used to treat lesions in vessels.However, difficulties are encountered in navigating tortuous anatomy andsafely crossing very tight lesions. Moreover, some lesions are longer inlength than others, and oftentimes multiple lesions need to be treatedin a single patient. Thus, it would be beneficial to have a ballooncatheter system having rapid exchange capabilities wherein a length ofthe balloon could be adjusted during the procedure and used to treatmultiple lesions of varying lengths. Known balloon dilation cathetersprovide limited focused force, do not address bifurcation lesions, andlack pushability and maneuverability.

SUMMARY OF THE INVENTION

Embodiments of a device for introduction into a vessel are generallydescribed including a main elongated element having a main elongatedelement proximal end and a main elongated element distal end, a balloonpositioned at the main elongated element distal end, the balloon havinga balloon proximal end, a balloon distal end, and an inflation lumentherethrough, a distal connecting element positioned at the distal endof the balloon to receive a guidewire during use, and a longitudinallymovable sheath positioned external to the main elongated element, thelongitudinally movable sheath having a distal end and a proximal end,wherein a position of the sheath distal end with respect to the balloondefines an exposed portion of the balloon that expands when fluid isdelivered to the balloon through the inflation lumen.

The sheath of the device may include a tapered end to provide a reduceddiameter entry profile for the device. When initially introduced intothe vessel, the sheath may be at a distal position covering the balloonto provide a reduced diameter tip where only the distal connectingelement is exposed for introduction over a guidewire. The distal end ofthe sheath may also include a tapered end with a soft edge that expandsupon retraction of the sheath over the balloon. The body of the sheathmay include a braided or helically wrapped coil to prevent an unexposedportion of the balloon from expanding when the sheath is positionedexternal to the unexposed portion of the balloon. The sheath may alsoinclude a polymeric liner or outer jacket in order to provide additionalstrength.

Embodiments as described herein may further include a core wireunslidingly attached to said main elongated element at a core wireattachment point including an internal core wire portion positionedwithin said main elongated element and an external core wire portionpositioned distally with respect to said internal core wire portion,said external core wire portion external to and running alongside saidballoon. The external core wire portion may further include a coilwrapped around at least a portion thereof, where the coil-wrappedportion is positioned adjacent to the balloon.

The device may also include one or more radiopaque markers to indicatethe position of the device within the vessel and a rotationalorientation. Accordingly, a first and second radiopaque marker may belongitudinally aligned, such as on the described core while, while athird radiopaque marker is positioned off the longitudinal axis, such ason an auxiliary elongate element or the distal connecting element.

Unless otherwise defined, all technical and scientific terms used hereinhave the same meaning as commonly understood by one of ordinary skill inthe art to which this invention belongs. Although methods and materialssimilar or equivalent to those described herein can be used in thepractice or testing of the present invention, suitable methods andmaterials are described below. In case of conflict, the patentspecification, including definitions, will control. In addition, thematerials, methods, and examples are illustrative only and not intendedto be limiting.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and further advantages of the present invention may be betterunderstood by referring to the following description in conjunction withthe accompanying drawings in which:

FIG. 1A is a schematic illustration of a system for treatment of avessel, in accordance with embodiments of the present invention;

FIGS. 1B-1D are cross-sectional illustrations of the system of FIG. 1A;

FIG. 1E is a perspective illustration of the system of FIG. 1A;

FIG. 1F is a schematic illustration of the system of FIG. 1A, with anocclusion balloon;

FIG. 1G is a cross-sectional illustration of the system of FIG. 1F;

FIG. 2 is a schematic illustration of a system for treatment of avessel, in accordance with other embodiments of the present invention;

FIG. 3 is a schematic illustration of a system for treatment of avessel, in accordance with yet additional embodiments of the presentinvention;

FIG. 4 is a schematic illustration of a system for treatment of avessel, in accordance with yet additional embodiments of the presentinvention;

FIGS. 5A and 5B are illustrations of a core wire, in accordance withembodiments of the present invention;

FIGS. 6A-6D are cross-sectional illustrations of a distal portion of thesystems of FIGS. 1-4;

FIGS. 7A-7F are schematic illustrations of the steps of a method oftreating a vessel, in accordance with embodiments of the presentinvention;

FIGS. 8A-8C are schematic illustrations of the steps of a method oftreating a vessel, in accordance with additional embodiments of thepresent invention;

FIGS. 9A-9C are schematic illustrations of the steps of a method oftreating a vessel, in accordance with additional embodiments of thepresent invention;

FIGS. 10A-10C are schematic illustrations of the steps of a method oftreating a bifurcated vessel, in accordance with additional embodimentsof the present invention;

FIGS. 11A-11D are schematic illustrations of a system in accordance withadditional embodiments of the present invention, wherein a sheath ispositioned over a main elongated element;

FIGS. 12A and 12B are illustrations of the sheath of FIGS. 11A-11D, inaccordance with embodiments of the present invention;

FIG. 13 is an illustration of an edge of the sheath of FIGS. 11A-11D;

FIG. 14 is an illustration of a proximal end of the system of FIGS.11A-11D; and

FIGS. 15A-15D are illustrations of the steps of a method of treating avessel, in accordance with additional embodiments of the presentinvention.

It will be appreciated that for simplicity and clarity of illustration,elements shown in the drawings have not necessarily been drawnaccurately or to scale. For example, the dimensions of some of theelements may be exaggerated relative to other elements for clarity orseveral physical components may be included in one functional block orelement. Further, where considered appropriate, reference numerals maybe repeated among the drawings to indicate corresponding or analogouselements. Moreover, some of the blocks depicted in the drawings may becombined into a single function.

DETAILED DESCRIPTION

In the following detailed description, numerous specific details are setforth in order to provide a thorough understanding of the presentinvention. It will be understood by those of ordinary skill in the artthat the present invention may be practiced without these specificdetails. In other instances, well-known methods, procedures, componentsand structures may not have been described in detail so as not toobscure the present invention.

The present invention is directed to systems and methods for treatmentof a vessel including an adjustable balloon length. The principles andoperation of a system and methods according to the present invention maybe better understood with reference to the drawings and accompanyingdescriptions.

Before explaining at least one embodiment of the present invention indetail, it is to be understood that the invention is not limited in itsapplication to the details of construction and the arrangement of thecomponents set forth in the following description or illustrated in thedrawings. The invention is capable of other embodiments or of beingpracticed or carried out in various ways. Also, it is to be understoodthat the phraseology and terminology employed herein are for the purposeof description and should not be regarded as limiting.

It is appreciated that certain features of the invention, which are, forclarity, described in the context of separate embodiments, may also beprovided in combination in a single embodiment. Conversely, variousfeatures of the invention, which are, for brevity, described in thecontext of a single embodiment, may also be provided separately or inany suitable subcombination.

Reference is now made to FIGS. 1A and 1E, which are a schematic andperspective illustration, respectively, of a system 10 for treatment ofa vessel, in accordance with embodiments of the present invention.System 10 includes a main elongated element 12 having a proximal end 14and a distal end 16. In some embodiments of the present invention, mainelongated element 12 is a catheter shaft. A balloon 24 is positioned atdistal end 16 of main elongated element 12. Balloon 24 can be comprisedof a variety of diameters, ranging from 1.25-10.0 mm, for example, and avariety of lengths, ranging from 10 mm to 30 cm, for example. Longballoons may be particularly useful for treating peripheral lesions,which often have long diseased portions. System 10 further includes anauxiliary elongated element 18 configured to receive a guidewire 48therethrough. Auxiliary elongated element 18 has a proximal end 20 witha proximal exit point 21 for guidewire 48 and a distal end 22 with adistal exit point 23 for guidewire 48. In some embodiments, at least aportion of auxiliary elongated element 18 is positioned within mainelongated element 12 so as to reduce the outer profile of system 10.Distal end 22 of auxiliary elongated element 18 is proximal to balloon24 such that guidewire 48, when positioned through auxiliary elongatedelement 18, exits distal exit point 23 and runs alongside and externalto balloon 24. This configuration provides for a focused force elementalongside balloon 24, as will be described further hereinbelow. In someembodiments, such as the one shown in FIGS. 1A and 1E, auxiliaryelongated element 18 runs along the length of main elongated element 12to a proximal guidewire port 50. This configuration provides anover-the-wire type of configuration. In this embodiment, auxiliaryelongated element 18 may be used for items other than a guidewire, sucha drug delivery, sensors, or to hold a mandrel therein so as to provideadditional rigidity to the system when needed. In the embodiment whereinguidewire 48 is used, guidewire 48 positioned through distal exit point23 forms a crotch point 46 at or near a proximal end of balloon 24. Thepresence of a crotch point may be useful, for example, for anchoringsystem 10 within a side branch to avoid slippage within the vessel to betreated, or to provide for precise positioning of system 10 at abifurcation.

In some embodiments, main elongated element 12 is stiffer proximallythan distally. This may be accomplished, for example, by using a metalhypotube in the proximal portion and a polymer or other flexiblematerial in the distal portion. This configuration provides moreflexibility at the distal end to allow for easier maneuverabilitythrough tortuous vessels, while maintaining rigidity at a proximal endfor pushability. However, if the distal portion of main elongatedelement 12 is too flexible, it will be difficult to push through thevessels. Thus, system 10 further includes a core wire 28, which providesenhanced pushability of system 10 without significantly reducing theflexibility of system 10. Core wire 28 is provided in the flexibleportion, and may terminate at the stiff portion when no longer neededfor rigidity. In other embodiments, main elongated element 12 isrelatively flexible along all or most of its length, by using a flexiblepolymer or other flexible material to form main elongated element 12. Inthese embodiments, core wire 28 may run along an entire length of mainelongated element 12 and may vary in diameter along the length so as toprovide increased rigidity at proximal end 14. In some embodiments, theflexible shaft may also be braided or otherwise strengthened to providesufficient rigidity.

In embodiments of the present invention, core wire 28 has a portionpositioned within main elongated element 12, referred to herein asinternal core wire portion 30, and a portion positioned external to mainelongated element 12, referred to herein as external core wire portion32. Internal core wire portion 30 is proximal to external core wireportion 32, and is attached to main elongated element 12 at an internalcore wire attachment point 44. As discussed further below with respectto FIG. 5A, external core wire portion 32 may be configured with a coil34. For embodiments wherein main elongated element 12 is comprised of arelatively flexible distal portion and a relatively rigid proximalportion, internal core wire attachment point 44 is located at aninterface between the stiff proximal portion and the flexible distalportion, for example, a distal end of the hypotube. In embodimentswherein main elongated element is mostly or completely comprised offlexible material, internal core wire attachment point 44′ is located atproximal end 14 of system 10. However, it should be readily apparentthat internal core wire attachment point 44 may be located at anylocation along the length of main elongated element 12. Moreover,multiple internal core wire attachment points 44 may be included. At alocation proximal to balloon 24, internal core wire portion 30 exitsmain elongated element 12 and becomes external core wire portion 32.This location is referred to herein as a core wire exit point 42. In oneembodiment, core wire exit point 42 is at a distal end of main elongatedelement 12. In other embodiments, core wire exit point 42 is at otherlocations along main elongated element 12 (but in most cases proximal toballoon 24). Distal to core wire exit point 42, external core wireportion 32 is positioned alongside balloon 24, and a distal end ofexternal core wire portion 32 is attached to a distal tip 25 of balloon24. Several attachment or bonding locations provide transmission offorces through the length of the catheter, and thus enhance overalltorquability and rotatability. In particular, bonding can be done at anyor all of the following locations: at distal tip 25 of balloon 24, atcore wire exit point 42, and at internal core wire attachment point 44.Additional attachment points may be included as well. It should be notedthat the use of an internal core wire makes it possible to have a longerflexible (polymeric or other) portion or even a completely flexibleshaft, enhancing overall flexibility of system 10.

In some embodiments, a triangular marker configuration is used torotationally orient the system 10. Rotational orientation may benecessary, for example, when re-entering a guidewire into a vessel afterentry into or creation of a sub-intimal lumen during treatment. Otherinstances requiring rotational orientation may occur as well. As such, amarker configuration which can aid in rotational positioning of system10 would be beneficial. As shown in FIG. 1A, a first radiopaque marker80 and a second radiopaque marker 82 are positioned on a section of corewire 28, and a third radiopaque marker 84 is positioned on auxiliaryelongated element 18 at distal exit point 23. As described above, corewire 28 may be attached at multiple points along main elongated element12, which is important both for general rigidity and for stability andmaintained alignment of first and second radiopaque markers 80 and 82.In one rotational position, markers 80 and 82 are approximately alignedalong a longitudinal axis, while marker 84 is on a differentlongitudinal axis than markers 80 and 82. If system 10 is rotated 90degrees from the first position, all three markers 80, 82 and 84 areroughly aligned. Thus, by viewing the relative positions of markers 80,82 and 84, it is possible to determine a rotational orientation ofsystem 10 and as such, a rotational position of guidewire 48. A constantlongitudinal distance between markers 80, 82 and 84 may be maintained toclearly mark the rotational relationships between the markers.

System 10 further includes a distal connecting element 38 at distal tip25 of balloon 24. Distal connecting element 38 may be a short rail,ranging in length from 2-20 mm, or may be a longer rail, ranging inlength from 1-4 cm, and more specifically in a range of approximately2.5 cm. A longer distal connecting element 38 may provide additionalsupport for crossing tight or chronic occlusions. Distal connectingelement 38 may be bonded to distal tip 25 such that the proximal end ofdistal connecting element 38 is distal to balloon 24. In the case of alonger rail, distal connecting element 38 may then extend distally pastballoon 24. A radiopaque marker 86 may be included on distal connectingelement 38. This may be particularly useful in case guidewire 48 slipsout of distal connecting element 38 and must be guided back in. Athree-way bond may be used to attach distal connecting element 38,balloon 24 and external core wire portion 32, all together. Distalconnecting element 38 may be tapered toward its distal end to facilitatepassage through tight stenoses. Distal connecting element 38 ispositioned at a rotational distance from auxiliary elongated element 18and from external core wire portion 32, and is configured to hold atracking guidewire 49 therethrough. In some embodiments, distalconnecting element 38, auxiliary elongated element 18 and external corewire portion 32 are positioned approximately 120° from one another. Inother embodiments, other rotational distances may be used, such thatthere is some rotational separation between them. In this way, guidewire48, tracking guidewire 49 and core wire 32 may all lie alongside balloon24 at different rotational positions along balloon 24 when balloon 24 isin its expanded state. Although the separations between guidewire 48,tracking guidewire 49 and core wire 32 are not required to be anyspecific amounts, it should be apparent that the distances between themshould be sufficient to provide separate wires alongside severaldifferent areas of balloon 24. Each of these wires can then provide afocused force to help crack difficult lesions, as will be explainedfurther hereinbelow. It should be noted that in some embodiments,guidewire 48 and tracking guidewire 49 may be of different sizes.

Reference is now made to FIGS. 1B-1D, which are cross-sectionalillustrations of system 10 shown at section A-A, in accordance withseveral embodiments of the present invention. As shown in FIG. 1B, aninterior portion of main elongated element 12 serves as an inflationlumen 26, providing fluid communication between an inflation port 52located at proximal end 14 of main elongated element 12 and balloon 24located at distal end 16 of main elongated element 12. In someembodiments, a portion of the interior of main elongated element 12 issectioned off for use as inflation lumen 26, as shown in FIG. 1C and inFIG. 1D, wherein only the sectioned off inflation lumen 26 is in fluidcommunication with inflation port 52. Auxiliary elongated element 18 ispositioned within main elongated element along an edge thereof. Thecross-sectional views of FIGS. 1B-1D show auxiliary elongated element 18with guidewire 48 positioned therein. Internal core wire portion 30 ispositioned within main elongated element 12. In some embodiments, asshown in FIGS. 1B and 1C, internal core wire portion 30 is positionedalong an edge of main elongated element 12. In other embodiments, asshown in FIG. 1D, internal core wire portion 30 is positioned in acenter of main elongated element 12. It should be readily apparent,however, that at core wire attachment point 44 and at core wire exitpoint 42, the core wire is in contact with or close proximity to an edgeof main elongated element 12. Tracking guidewire 49 is shown external tomain elongated element 12.

Reference is now made to FIGS. 1F and 1G, which are schematic andcross-sectional illustrations of system 10 further including anocclusion balloon 54. Occlusion balloon 54 is positioned around mainelongated element 12 and is proximal to auxiliary element distal exitpoint 23. As shown in FIG. 1F, an inflation lumen 27 provides fluidcommunication between an inflation port 56 located at proximal end 14 ofmain elongated element 12 and occlusion balloon 54 located along themain elongated element 12. Occlusion balloon 54 may be used totemporarily occlude blood flow proximal to occlusion balloon 54, and toenable introduction of an item or a substance into the vessel at thelesion site via auxiliary elongated element 18. In some embodiments, theitem is a treatment device, such as a guidewire with an ablation tip orany other treatment device. In some embodiments, the substance iscontrast media. In other embodiments, the substance is a therapeuticdrug or medicated solution. In some embodiments, multiple ports 19 maybe included on auxiliary elongated element 18, distal to occlusionballoon 54. These multiple ports 19 may enable spraying of a substancesuch as contrast media, drugs, medicated solutions, etc.

Reference is now made to FIG. 2, which is a schematic illustration ofsystem 10, wherein distal connecting element 38 is aligned withauxiliary elongated element 18, such that guidewire 48 may be positionedthrough distal connecting element 38 and further through auxiliaryelongated element 18, and out through auxiliary elongated elementproximal exit point 21. Thus, only one guidewire is used in theconfiguration shown in FIG. 2. This design provides a single guidewireenclosure split into two sections—one at the distal end and one at theproximal end of balloon 24—in order to reduce the profile of system 10in the vicinity of balloon 24 during introduction of system 10 into avessel. Guidewire 48, while positioned within distal connecting element38 and auxiliary elongated element 18, can serve as a focused force tohelp crack difficult lesions and may also be used as a trackingguidewire for advancing system 10 into the vessel.

Reference is now made to FIG. 3, which is a schematic illustration of asystem 100, in accordance with additional embodiments of the presentinvention. System 100 includes a main elongated element 112 having aproximal end 114 and a distal end 116. In some embodiments of thepresent invention, main elongated element 112 is a catheter shaft. Aballoon 124 is positioned at distal end 116 of main elongated element112. An interior portion of main elongated element 112 serves as aninflation lumen 126, providing fluid communication between an inflationport 152 located at proximal end 114 of main elongated element 112 andballoon 124 located at distal end 116 of main elongated element 112.Balloon 124 can be comprised of a variety of diameters, ranging from1.25-10.0 mm, for example, and a variety of lengths, ranging from 10 mmto 30 cm, for example. Long balloons may be particularly useful fortreating peripheral lesions, which often have long diseased portions.System 100 further includes an auxiliary elongated element 118configured to receive a guidewire 48 therethrough. Auxiliary elongatedelement 118 has a proximal end 120 with a proximal exit point 121 forguidewire 48 and a distal end 122 with a distal exit point 123 forguidewire 48. In some embodiments, at least a portion of auxiliaryelongated element 118 is positioned within main elongated element 112 soas to reduce the outer profile of system 100. Distal end 122 ofauxiliary elongated element 118 is proximal to balloon 124 such thatguidewire 48, when positioned through auxiliary elongated element 118,exits distal exit point 123 and runs alongside and external to balloon124. This configuration provides for a focused force element alongsideballoon 124, as will be described further hereinbelow. In someembodiments, such as the one shown in FIG. 3, auxiliary elongatedelement 118 is relatively short, extending 5-30 cm, and in someembodiments approximately 20 cm. This configuration enables rapidexchange in cases when system 100 may need to be retracted and adifferent device reinserted over guidewire 48. In some embodiments,auxiliary elongated element 118 is a solid piece rather than a lumen,and is used for enhanced bonding of a core wire 128, as will bedescribed hereinbelow. In one embodiment, guidewire 48 positionedthrough distal exit point 123 forms a crotch point 146 at or near aproximal end of balloon 124. The presence of a crotch point may beuseful, for example, for anchoring system 100 within a side branch toavoid slippage within the vessel to be treated, or to provide forprecise positioning of system 100 at a bifurcation.

In some embodiments, main elongated element 112 is stiffer proximallythan distally. This may be accomplished, for example, by using a metalhypotube in the proximal portion and a polymer or other flexiblematerial in the distal portion. This configuration provides moreflexibility at the distal end to allow for easier maneuverabilitythrough tortuous vessels, while maintaining rigidity at a proximal endfor pushability. However, if the distal portion of main elongatedelement 112 is too flexible, it will be difficult to push through thevessels. Thus, system 100 further includes a core wire 128, whichprovides enhanced pushability of system 100 without significantlyreducing the flexibility of system 100. Core wire 128 is provided in theflexible portion, and may terminate at the stiff portion when no longerneeded for rigidity. In other embodiments, main elongated element 112 isrelatively flexible along all or most of its length, by using a flexiblepolymer or other flexible material to form main elongated element 112.In these embodiments, core wire 128 may run along an entire length ofmain elongated element 112 and may vary in diameter along the length soas to provide increased rigidity at proximal end 114. In someembodiments, the flexible shaft may also be braided or otherwisestrengthened to provide sufficient rigidity.

In embodiments of the present invention, core wire 128 has a portionpositioned within main elongated element 112, referred to herein asinternal core wire 130, and a portion positioned external to mainelongated element 112, referred to herein as external core wire 132. Forembodiments wherein main elongated element 112 is comprised of arelatively flexible distal portion and a relatively rigid proximalportion, internal core wire attachment point 144 is located at aninterface between the stiff proximal portion and the flexible distalportion, for example, a distal end of the hypotube. In embodimentswherein main elongated element is mostly or completely comprised offlexible material, internal core wire attachment point 144′ is locatedat proximal end 114 of system 100. However, it should be readilyapparent that internal core wire attachment point 144 may be located atany location along the length of main elongated element 112. Moreover,multiple internal core wire attachment points 144 may be included. At alocation proximal to balloon 124, internal core wire 130 exits mainelongated element 112 and becomes external core wire 132. This locationis referred to herein as a core wire exit point 142. In one embodiment,core wire exit point 142 is at a distal end of main elongated element112 (but in most cases proximal to balloon 124). In other embodiments,core wire exit point 142 is at other locations along main elongatedelement 112. Distal to core wire exit point 142, external core wire 132is positioned alongside balloon 124, and a distal end of external corewire 132 is attached to a distal tip 125 of balloon 124. Severalattachment or bonding locations provide transmission of forces throughthe length of the catheter, and thus enhance overall torquability androtatability. In particular, bonding can be done at any or all of thefollowing locations: at a distal tip 125 of balloon 124, at core wireexit point 142, and at internal core wire attachment point 144.Additional attachment points may be included as well. Bonding may bedone by bonding auxiliary elongated element 118, and core wire 128together. It should be noted that the use of an internal core wire makesit possible to have a longer flexible (polymeric or other) portion oreven a completely flexible shaft, enhancing overall flexibility ofsystem 100. As described further with respect to FIG. 5A, external corewire portion 132 may be configured with a coil 134.

System 100 further includes a distal connecting element 138 at distaltip 125 of balloon 124. Distal connecting element 138 may be a shortrail, ranging in length from 2-20 mm, or may be a longer rail, rangingin length from 1-4 cm, and more specifically in a range of approximately2.5 cm. A longer distal connecting element 138 may provide additionalsupport for crossing tight or chronic occlusions. Distal connectingelement 138 may be bonded to distal tip 125 such that the proximal endof distal connecting element 138 is distal to balloon 124. In the caseof a longer rail distal connecting element 138 may then extend distallypast balloon 124. A radiopaque marker may be included on distalconnecting element 138. This may be particularly useful in caseguidewire 48 slips out of distal connecting element 138 and must beguided back in. A three-way bond may be used to attach distal connectingelement 138, balloon 124 and core wire 132 all together. Distalconnecting element 138 may be tapered toward its distal end tofacilitate passage through tight stenoses. Distal connecting element 138is aligned with auxiliary elongated element 118, such that guidewire 48may be positioned through distal connecting element 138 and furtherthrough auxiliary elongated element 118, and out through auxiliaryelongated element proximal exit point 121. Thus, only one guidewire isused in the configuration shown in FIG. 3. This design provides a singleguidewire enclosure split into two sections—one at the distal end andone at the proximal end of balloon 124—in order to reduce the profile ofsystem 100 in the vicinity of balloon 124 during introduction of system100 into a vessel. Guidewire 48, while positioned within distalconnecting element 138 and auxiliary elongated element 118, can serve asa focused force to help crack difficult lesions and may also be used asa tracking guidewire for advancing system 100 into the vessel.

Reference is now made to FIG. 4, which is a schematic illustration of asystem 200 for treatment of a vessel, in accordance with yet additionalembodiments of the present invention. The embodiment shown in FIG. 4 hasa reduced profile due to the use of a fixed wire balloon, and may beparticularly useful for smaller peripheral vessels such asinfra-popliteal vessels, for example. System 200 includes a mainelongated element 212 having a proximal end 214 and a distal end 216. Insome embodiments of the present invention, main elongated element 212 isa catheter shaft. A balloon 224 is positioned at distal end 216 of mainelongated element 212. An interior portion of main elongated element 212serves as an inflation lumen 226, providing fluid communication betweenan inflation port 252 located at proximal end 214 of main elongatedelement 212 and balloon 224 located at distal end 216 of main elongatedelement 212. Balloon 224 can be comprised of a variety of diameters,ranging from 1.25-10.0 mm, for example, and a variety of lengths,ranging from 10 mm to 30 cm, for example. Long balloons may beparticularly useful for treating peripheral lesions, which often havelong diseased portions. In the embodiment depicted in FIG. 4, balloon224 is a fixed wire balloon. In one embodiment, balloon 224 is a fixedwire balloon as is commonly known in the art. An example of such aballoon is the type used for the Ace™ Balloon Catheter of BostonScientific Corporation (Natick, Mass., USA). In another embodiment,balloon 224 is any balloon with a fixed wire 240 attached thereto.System 200 further includes an auxiliary elongated element 218configured to receive a guidewire 48 therethrough. Auxiliary elongatedelement 218 has a proximal end 220 with a proximal exit point 221 forguidewire 48 and a distal end 222 with a distal exit point 223 forguidewire 48. In some embodiments, at least a portion of auxiliaryelongated element 218 is positioned within main elongated element 212 soas to reduce the outer profile of system 200. Distal end 222 ofauxiliary elongated element 218 is proximal to balloon 224 such thatguidewire 48, when positioned through auxiliary elongated element 218,exits distal exit point 223 and runs alongside and external to balloon224. This configuration provides for a focused force element alongsideballoon 224, as will be described further hereinbelow. In someembodiments, such as the one shown in FIG. 4, auxiliary elongatedelement 218 is relatively short, extending 5-30 cm, and in someembodiments approximately 20 cm. This configuration enables rapidexchange in cases when system 200 may need to be retracted and adifferent device reinserted over guidewire 48. In other embodiments,auxiliary elongated element 218 may continue proximally along the entirelength of main elongated element 212 for an over-the-wire configuration,such as described above with reference to FIG. 1A. In one embodiment,guidewire 48 positioned through distal exit point 223 forms a crotchpoint 246 at or near a proximal end of balloon 224. The presence of acrotch point may be useful, for example, for anchoring system 200 withina side branch to avoid slippage within the vessel to be treated, or toprovide for precise positioning of system 100 at a bifurcation.

In some embodiments, main elongated element 212 is stiffer proximallythan distally. This may be accomplished, for example, by using a metalhypotube in the proximal portion and a polymer or other flexiblematerial in the distal portion. This configuration provides moreflexibility at the distal end to allow for easier maneuverabilitythrough tortuous vessels, while maintaining rigidity at a proximal endfor pushability. However, if the distal portion of main elongatedelement 212 is too flexible, it will be difficult to push through thevessels. Thus, system 200 further includes a core wire 228, whichprovides enhanced pushability of system 200 without significantlyreducing the flexibility of system 200. Core wire 228 is provided in theflexible portion, and may terminate at the stiff portion when no longerneeded for rigidity. In other embodiments, main elongated element 212 isrelatively flexible along all or most of its length, by using a flexiblepolymer or other flexible material to form main elongated element 212.In these embodiments, core wire 228 may run along an entire length ofmain elongated element 212 and may vary in diameter along the length soas to provide increased rigidity at proximal end 214. In someembodiments, the flexible shaft may also be braided or otherwisestrengthened to provide sufficient rigidity.

In embodiments of the present invention, core wire 228 has a portionpositioned within main elongated element 212, referred to herein asinternal core wire 230, and a portion positioned external to mainelongated element 212, referred to herein as external core wire 232. Asdiscussed further below with respect to FIG. 5A, external core wireportion 232 may be configured with a coil 234. For embodiments whereinmain elongated element 212 is comprised of a relatively flexible distalportion and a relatively rigid proximal portion, internal core wireattachment point 244 is located at an interface between the stiffproximal portion and the flexible distal portion, for example, a distalend of the hypotube. In embodiments wherein main elongated element ismostly or completely comprised of flexible material, internal core wireattachment point 244 is located at proximal end 214 of system 200.However, it should be readily apparent that internal core wireattachment point may be located at any location along the length of mainelongated element 212. Moreover, multiple internal core wire attachmentpoints 244 may be included. At a location proximal to balloon 224,internal core wire 230 exits main elongated element 212 and becomesexternal core wire 232. This location is referred to herein as a corewire exit point 242. In one embodiment, core wire exit point 242 is at adistal end of main elongated element 212 (but in most cases proximal toballoon 224). In other embodiments, core wire exit point 242 is at otherlocations along main elongated element 212. Distal to core wire exitpoint 242, external core wire 232 is positioned alongside balloon 224,and a distal end of external core wire 232 is attached to a distal tip225 of balloon 224. Several attachment or bonding locations providetransmission of forces through the length of the catheter, and thusenhance overall torquability and rotatability. In particular, bondingcan be done at any or all of the following locations: at a distal tip ofballoon 224, at core wire exit point 242, and at internal core wireattachment point 244. Additional attachment points may be included aswell. It should be noted that the use of an internal core wire makes itpossible to have a longer flexible (polymeric or other) portion or evena completely flexible shaft, enhancing overall flexibility of system200. In some embodiments, external core wire 232 and fixed wire 240 arecomprised of the same wire. In other embodiments, some or all ofexternal core wire 232 and fixed wire 240 are separate pieces of wirewhich are connected at the distal tip 225 of balloon 224.

In all of the systems described above, a hydrophilic coating may beadded externally to provide ease of insertion.

Reference is now made to FIG. 5A and FIG. 5B, which are schematicillustrations of external core wire portion 32, 132, 232 in accordancewith embodiments of the present invention. As shown in FIG. 5A, externalcore wire portion 32, 132 or 232 is configured with a wire portion 60and a coil 34. Wire portion 60 includes a proximal wire section 62, amid-wire section 64 and a distal wire section 66. Proximal and distalwire sections 62 and 66 both have a diameter D1 which is greater than adiameter D2 of mid-wire section 64. Coil 34 is wrapped around mid-wiresection 64. When in position on system 10, 100, 200, mid-wire section 64with coil 34 runs alongside balloon 24, 124, 224. This configurationprovides enhanced flexibility as well as gripping at the lesion so thatslippage of balloon 24, 124, 224 against the lesion is reduced.Moreover, in some embodiments, coil 34 is comprised of radiopaquematerial, and thus acts as a marker for positioning of system 10, 100 or200.

Reference is now made to FIG. 5B, which is an illustration of externalcore wire portion 32, 132, 232 in accordance with another embodiment ofthe present invention. Core wire 32, 132, 232 may be a wire having atleast one radiopaque marker 36 thereon. Multiple markers 36 may be used,and may be spaced at optimal locations such as at a proximal end and adistal end of balloon 24, for example.

Although external core wire portion 32 is positioned external to balloon24 when balloon 24 is in its inflated state, as shown in FIGS. 1A, 2, 3and 4, when balloon 24 is in its deflated state (i.e., during insertionof system 10 into the body), external core wire portion 32 may bepositioned within folds of balloon 24. Reference is now made to FIG.6A-6D, which are cross-sectional illustrations along line B-B of system10 showing external core wire portion 32, guidewire 48, trackingguidewire 49, and balloon 24 in its deflated state (FIGS. 6A and 6B) andits inflated state (FIGS. 6C and 6D). It should be readily apparent thatsimilar configurations are possible for systems 100 and 200 as well. Asshown in FIGS. 6A and 6B, when balloon 24 is in its deflatedconfiguration, external core wire portion 32 is positioned within foldsof balloon 24. If a guidewire 48 and/or tracking guidewire 49 arepresent, guidewire 48 and tracking guidewire 49 can be seen alongsideballoon 24. As shown in FIG. 6C, when balloon 24 is expanded, externalcore wire portion 32 is positioned alongside balloon 24. The externalposition of external core wire portion 32 with respect to balloon 24provides an area of focused force for cracking or breaking up hard ordifficult lesions. Guidewire 48 and tracking guidewire 49 may be used toprovide an additional area of focused force. In some embodiments,guidewire 48 is positioned at a rotational distance from external corewire portion 32 so as to provide multiple areas of focused force aroundsystem 10. For example, auxiliary elongated element 18 may be positionedapproximately 180 degrees from external core wire portion 32, orapproximately 120 degrees from external core wire portion 32 andapproximately 120 degrees from tracking guidewire 49, although it shouldbe readily apparent that many different rotational distances arepossible.

Reference is now made to FIG. 6D, which is a cross-sectionalillustration along line B-B, in accordance with another embodiment. Inthis embodiment, additional external core wires 33 and 35 are present aswell. Although shown with three external core wires, any suitable numberof core wires may be used. In one embodiment, core wire 28 is split intomultiple wires at core wire exit point 42, and the multiple core wiresare bundled together at distal end 16 of system 10. In an alternativeembodiment, multiple core wire exit points 42 are spaced around mainelongated element 12, and multiple core wires exit through the multiplecore wire exit points. They are then bundled together at distal tip 25of balloon 24.

Reference is now made to FIGS. 7A-7E, which are schematic illustrationsof the steps of a method of treating a vessel, in accordance withembodiments of the present invention. A vessel 300 having a lesion 302is accessed via tracking guidewire 49 as shown in FIG. 7A. Trackingguidewire 49 is backloaded onto system 10 by placing tracking guidewire49 through distal connecting element 38, and system 10 is advanced overtracking guidewire 49 to the vicinity of lesion 302, as shown in FIG.7B. Next, an additional guidewire 48 may be positioned through auxiliaryelongated element 18, and advanced until a distal end of guidewire 48 isdistal to balloon 24, as shown in FIG. 7C. In some instances, whenguidewire 48 is difficult to advance to this distal location, system 10may be advanced distally past lesion 302, such that distal exit point 23of auxiliary elongated element 18 is beyond lesion 302. Guidewire 48 isthen advanced through auxiliary elongated element 18. System 10 may thenbe pulled back proximally so that guidewire 48 and tracking guidewire 49are adjacent balloon 24 and are in a vicinity of lesion 302. Balloon 24is then expanded, as shown in FIG. 7D. Expansion of balloon 24 causesexternal core wire portion 32 to be released from within folds ofballoon 24. Expansion of balloon 24 further causes guidewire 48,tracking guidewire 49 and external core wire portion 32 to be pushed upagainst lesion 302 in three separate rotational positions around thevessel and the lesion. The presence of guidewire 48, tracking guidewire49, and/or external core wire portion 32 provides a focused force toenable the user to crack hard lesions at low pressure before balloon 24is fully inflated. Doing so allows vessel stretching to occur at a lowerstrain rate, thus minimizing the trauma associated with balloondilatation.

In some embodiments, auxiliary elongated lumen 18 may further be used toprovide an item or substance to the vessel. Reference is now made toFIG. 7E, which is a schematic illustration of system 10 positionedinside vessel 300. After the lesion has been cracked or pushed open viaballoon 24 and/or external core wire portion 32 and/or guidewire 48,and/or tracking guidewire 49, balloon 24 may then be deflated. In someembodiments, guidewire 48 is retracted to provide an open lumen fordelivery of an object or drug to vessel 300. Occlusion balloon 54 isinflated, blocking the portion of vessel 300 which is proximal toocclusion balloon 54. Then, a drug, contrast media or other treatmentdevice may be inserted through auxiliary elongated element 18 and usedto treat vessel 300. In some embodiments, after deflating balloon 24,system 10 is advanced past the lesion, occlusion balloon 54 is inflatedand treatment is provided to a portion of vessel 300 which is distal tolesion 302. In yet another embodiment, as shown in FIG. 1A, system 10does not have occlusion balloon 54. After deflating balloon 24, system10 is advanced past the lesion. Balloon 24 is reinflated at low pressureto occlude vessel 300, and treatment is provided to a portion of vessel300 that is distal to lesion 302. In some embodiments, ports 19 mayprovide additional access for treatment of the vessel by sprayingtreatment solution, for example.

In some embodiments, auxiliary elongated element 18 may be used tointroduce a “buddy wire” for tortuous vessels. The “buddy wire” conceptis known in the art, and involves introducing a secondary wire alongsidea catheter to help straighten out curved vessels and ease the way forthe catheter. However, by using a system such as the ones describedherein, the “buddy wire” may be introduced within the catheter,minimizing the risk of puncture of the vessel or entanglement of thebuddy wire with the catheter. Moreover, systems of the present inventionmay also be used to introduce a second wire for bifurcations, whereinguidewire 48 introduced through auxiliary elongated element 18 andtracking guidewire 49 may both remain in the vessel. When the system isremoved from the body, guidewire 48 is prevented from entanglement withtracking guidewire 49 since guidewire 48 is positioned within auxiliaryelongated element 18. Thus, any crossing over which may occur isautomatically straightened out during removal of system 10. Anadditional use of system 10 is in cases where a practitioner encountersa “false lumen”. That is, if tracking guidewire 49 encounters an areawhich is not a true lumen, an additional guidewire 48 may be introducedthrough system 10 and through the true lumen. System 10 may then beretracted proximally, and advanced over guidewire 48 to cross thelesion.

Reference is now made to FIGS. 8A-8C, which are schematic illustrationsof the steps of a method of treating a vessel, in accordance withembodiments of the present invention. A vessel 300 having a lesion 302is accessed via guidewire 48, as shown in FIG. 8A. Guidewire 48 isbackloaded onto system 100 by placing guidewire 48 through distalconnecting element 138, and further positioning guidewire 48 throughauxiliary elongated element 118, as shown in FIG. 8B. In someembodiments, an introducer is used to help place guidewire 48 intodistal exit point of auxiliary elongated element 118. The introducer maybe, for example, a mandrel having a female end, which is pre-loaded intoboth auxiliary elongated element 118 and distal connecting element 138.When guidewire 48 is backloaded into distal connecting element 138, theproximal end of guidewire 48 is positioned within the female end of themandrel. The mandrel may then be pulled back proximally, leadingguidewire 48 into auxiliary elongated element 118. Guidewire 48 is thuspositioned through both distal connecting element 138 and throughauxiliary elongated element 118, and exits through auxiliary elongatedelement proximal exit point 121, which may be relatively close toauxiliary elongated element distal exit point 123 for rapid exchange asshown in FIG. 8B, or may be at the proximal end of main elongatedelement 112 for an over-the-wire configuration. System 100 is advancedover guidewire 48, and positioned such that balloon 124 is adjacentlesion 302, as shown in FIG. 8B. It should be noted that external corewire 132 is not shown in FIG. 8B during insertion, since it is foldedinto balloon 124. Balloon 124 is then inflated, which pushes bothguidewire 48 and external core wire 132 up against lesion 302. Thepresence of guidewire 48 and/or external core wire 132 provides afocused force to enable the user to crack hard lesions at low pressurebefore balloon 124 is fully inflated. Doing so allows vessel stretchingto occur at a lower strain rate, thus minimizing the trauma associatedwith balloon dilatation.

Reference is now made to FIGS. 9A-9C, which are schematic illustrationsof the steps of a method of treating a vessel, in accordance withembodiments of the present invention. A vessel 300 having a lesion 302is accessed via guidewire 48. Guidewire 48 is backloaded onto system 200by placing guidewire 48 through auxiliary elongated element 218.Guidewire 48 exits through auxiliary elongated element proximal exitpoint 221, which may be relatively close to auxiliary elongated elementdistal exit point 223 for rapid exchange as shown in FIGS. 9B and 9C, ormay be at the proximal end of main elongated element 212 for anover-the-wire configuration. System 200 is advanced over guidewire 48,and positioned such that balloon 224 is adjacent lesion 302, as shown inFIG. 9B. It should be noted that external core wire 232 is not shown inFIG. 9B during insertion, since it is folded into balloon 224. Balloon224 is then inflated, as shown in FIG. 9C, which pushes both guidewire48 and external core wire 232 up against lesion 302. The presence ofguidewire 48 and/or external core wire 232 provides a focused force toenable the user to crack hard lesions at low pressure before balloon 224is fully inflated. Doing so allows vessel stretching to occur at a lowerstrain rate, thus minimizing the trauma associated with balloondilatation. Alternatively, instead of introducing a guidewire, fixedwire 240 is used to cross the lesion. In this embodiment, auxiliaryelongated element 218 may optionally not be included. Balloon 224 isthen expanded, and external core wire 232 provides the focused force. Ifauxiliary elongated element 218 is present, a guidewire 48 mayadditionally be introduced through auxiliary elongated element 218 toprovide additional focused force. These forces may be useful in treatinga variety of lesions, including those found at renal or peripheralvessels, and may be useful for procedures requiring high forces such asvalvuloplasty. It should be readily apparent that when auxiliaryelongated element 218 is included, it may also be used as a conduit toprovide objects, treatment drugs, contrast media, guidewires, etc. tothe vessel.

In some embodiments, the systems of the present invention may be used totreat vessels at a bifurcation. Reference is now made to FIGS. 10A-10C,which are schematic illustrations of the steps of a method for treatinga bifurcated vessel, in accordance with embodiments of the presentinvention. First, tracking guidewire 49 is introduced into the mainvessel 300, as shown in FIG. 10A. Next, system 10 is advanced overtracking guidewire 49 by backloading tracking guidewire 49 throughdistal connecting element 38, as shown in FIG. 10B. A guidewire 48 maythen be advanced through auxiliary elongated element 18 and into abranch vessel 304. The main vessel lesion 302 may then be treated byinflating balloon 24, while branch vessel 304 is protected in case ofplaque shift or additional lesion portions extending into branch vessel304.

In alternative embodiments, system 100 is advanced over a guidewire 48by backloading guidewire 48 into both distal connecting element 138 andauxiliary elongated element 118. After treatment of lesion 302 in mainvessel 300, guidewire 48 may be pulled back proximally and introducedinto branch vessel 304. The balloon is deflated, the catheter isretracted along the guidewire, and the system is introduced into thebranch vessel. The balloon may then be reinflated so as to compress thelesion in the branch vessel. In an alternative method, the guidewire isintroduced into the branch vessel, and the catheter is advanced over theguidewire past the bifurcation and into the main vessel. The main vessellesion is then treated by inflating the balloon and compressing thelesion. The balloon is deflated, the catheter is retracted, andintroduced into the branch vessel such that the guidewire is positionedalongside the balloon. Upon inflation of the balloon, the guidewire iscompressed into the lesion site, and provides a focused force to enablethe user to crack hard lesions at low pressure before the balloon isfully inflated. This alternative method is possible using system 200with fixed wire 240, since fixed wire 240 may be used to cross thelesion at the main vessel while guidewire 48 is positioned in the branchvessel.

While certain features of the present invention have been illustratedand described herein, many modifications, substitutions, changes, andequivalents may occur to those of ordinary skill in the art. Forexample, a catheter for uses other than expansion of a balloon and/ordelivery of a stent may be used with the device of the presentinvention, such as a catheter for drug delivery at an ostium, forcauterization, or for any other treatment. It is, therefore, to beunderstood that the appended claims are intended to cover all suchmodifications and changes as fall within the true spirit of the presentinvention.

Reference is now made to FIGS. 11A-11C, which are schematicillustrations of a system 400, in accordance with yet additionalembodiments of the present invention. System 400 includes a mainelongated element 412 having a proximal end 414 and a distal end 416. Insome embodiments of the present invention, main elongated element 412 isa catheter shaft. A balloon 424 is positioned at distal end 416 of mainelongated element 412. As shown in FIG. 11B, an interior portion of mainelongated element 412 serves as an inflation lumen 426, providing fluidcommunication between an inflation port 452 located at proximal end 414of main elongated element 412 and balloon 424 located at distal end 416of main elongated element 412. Balloon 424 can be comprised of a varietyof diameters, ranging from 1.25-10.0 mm, for example, and a variety oflengths, ranging from 10 mm to 30 cm, for example. Long balloons may beparticularly useful for treating peripheral lesions, which often havelong diseased portions. In one embodiment, an auxiliary elongatedelement may be included within and along a length of main elongatedelement 412 for positioning of a mandrel for increased rigidity and/oras an additional bonding area. System 400 further includes a sheath 470coaxial to main elongated element 412. Sheath 470 has a proximal end 472and a distal end 474. Proximal end 472 is positioned near a proximal endof system 400 and may include a handle or other means for moving sheath470 via proximal end 472. Distal end 474 is positioned in a vicinity ofballoon 424. Sheath 470 is movable proximally and distally, as shown byarrow 471 such that sheath 470 may surround all or some of balloon 424.Sheath 470 is thus designed to act as a sizer for balloon 424, wherein aposition of sheath 470 will determine the size of balloon 424 to beexpanded. Sheath 470 is shown in FIG. 11A in a proximal position,wherein all of or a majority of balloon 424 is exposed and may thus beexpanded. Sheath 470 is shown in FIG. 11B in a more distal position,wherein a portion of balloon 424 is covered by sheath 470 and as such,upon expansion of balloon 424, only the portion distal to distal end 474of sheath 470 will expand. This configuration is shown in FIG. 11C.

System 400 may further include a core wire 428, which provides enhancedpushability of system 400 without significantly reducing the flexibilityof system 400. Core wire 428 may be provided in a flexible portion, andmay terminate at a stiff portion when no longer needed for rigidity, asdescribed above with respect to system 10 and FIGS. 1A-1G or may runalong an entire length of main elongated element 412 if necessary. Corewire 428 may vary in diameter along the length so as to provideincreased rigidity at proximal end 414. In some embodiments, theflexible shaft may also be braided or otherwise strengthened to providesufficient rigidity. The core wire 428 may be unslidingly attached tothe system 400 to provide the desired pushability.

In embodiments of the present invention, core wire 428 has a portionpositioned within main elongated element 412, referred to herein asinternal core wire portion 430, and a portion positioned external tomain elongated element 412, referred to herein as external core wireportion 432. Internal core wire portion 430 is proximal to external corewire portion 432, and is attached to main elongated element 412 at aninternal core wire attachment point 444. As discussed above with respectto FIG. 5A, external core wire portion 432 may be configured with a coil434. For embodiments wherein main elongated element 412 is comprised ofa relatively flexible distal portion and a relatively rigid proximalportion, internal core wire attachment point 444 is located at aninterface between the stiff proximal portion and the flexible distalportion, for example, a distal end of the hypotube. In embodimentswherein main elongated element 412 is mostly or completely comprised offlexible material, internal core wire attachment point 444 is located atproximal end 414 of system 400. However, it should be readily apparentthat internal core wire attachment point 444 may be located at anylocation along the length of main elongated element 412. Moreover,multiple internal core wire attachment points 444 may be included. Theattachment point 444 may be any engagement between the core wire 428 andthe system 400 that prevents the relative longitudinal movement of thecore wire 428 relative to the system 400 at the attachment point 444. Ata location proximal to balloon 424, internal core wire portion 430 exitsmain elongated element 412 and becomes external core wire portion 432.This location is referred to herein as a core wire exit point 442. Inone embodiment, core wire exit point 442 is at a distal end of mainelongated element 412. In other embodiments, core wire exit point 442 isat other locations along main elongated element 412 (but in most casesproximal to balloon 424). Distal to core wire exit point 442, externalcore wire portion 432 is positioned alongside balloon 424, and a distalend of external core wire portion 432 is attached to a distal tip 425 ofballoon 424. Several attachment or bonding locations providetransmission of forces through the length of the catheter, and thusenhance overall torquability and rotatability. In particular, bondingcan be done at any or all of the following locations: at distal tip 425of balloon 424, at core wire exit point 442, and at internal core wireattachment point 444. Additional attachment points may be included aswell. It should be noted that the use of an internal core wire makes itpossible to have a longer flexible (polymeric or other) portion or evena completely flexible shaft, enhancing overall flexibility of system400.

System 400 further includes a distal connecting element 438 at distaltip 425 of balloon 424. Distal connecting element 438 is a short rail,ranging in length from 2-25 mm, and may be bonded to distal tip 425 suchthat the proximal end of distal connecting element 438 is distal toballoon 424. A three-way bond may be used to attach distal connectingelement 438, balloon 424 and external core wire portion 432, alltogether. Distal connecting element 438 may be tapered toward its distalend to facilitate passage through tight stenoses. In some embodiments,distal connecting element 438 is positioned at a rotational distancefrom external core wire portion 432, and is generally cylindricallyshaped to hold a tracking guidewire 49 therethrough. In this way,tracking guidewire 49 and core wire 432 may both lie alongside balloon424 at different rotational positions along balloon 424 when balloon 424is in its expanded state. Although the separation between trackingguidewire 49 and core wire 432 is not required to be any specificamount, it should be apparent that the distance between them should besufficient to provide separate wires alongside different areas ofballoon 424. Each of these wires can then provide a focused force tohelp crack difficult lesions, as will be explained further hereinbelow.

It is a particular feature of the present invention, that by trackingsystem 400 over tracking guidewire 49, which is positioned within distalconnecting element 438, rapid exchange capabilities are maintained. Therapid exchange capability, along with a variable length balloon whoselength is controlled via an outer sheath, is particularly advantageousand had previously not been contemplated since rapid exchange cathetersgenerally have a tracking guidewire exit point along a length of thecatheter, and this exit point would tend to be trapped by an outersheath such as the one described herein.

Reference is now made to FIG. 11D, which is a cross-sectionalillustration of system 400 shown at section A-A, in accordance withembodiments of the present invention. Sheath 470 surrounds mainelongated element 412. Tracking guidewire 49 is outside of sheath 470.An inflation lumen 426 may be an interior portion of main elongatedelement 412, with core wire 430 positioned therein.

Reference is now made to FIGS. 12A-12B, which are schematicillustrations of sheath 470 in accordance with embodiments of thepresent invention. Sheath 470 must be constructed such that it is strongenough to resist forces generated by inflation of balloon 424. Thus,sheath 470′ may be comprised of coiled material, as in FIG. 12A, sheath470″ may be comprised of a braided material, as in FIG. 12B, or anyother suitable material for providing sufficient resistance while stillretaining flexibility. In some embodiments, sheath 470 may include apolymeric liner or outer jacket in order to provide additional strength.

Distal end 474 of sheath 470 includes an edge 475. In order to avoidintimal damage during insertion and movement of sheath 470, edge 475 maybe tapered, as shown in FIG. 13. In some embodiments, a hydrogel may beapplied to either balloon 424 or an interior portion of sheath 470 forlubrication. In one embodiment, a soft edge may be used. In oneembodiment, sheath 470 may be initially positioned in its most distalposition, covering all of balloon 424, so that during insertion the riskof intimal damage is minimized. In this embodiment, sheath 470 is thenretracted upon arrival at the treatment site, so as to expose thedesired balloon length.

Reference is now made to FIG. 14, which is an illustration of proximalend 472 of sheath 470. Main elongated element 412 includes markings 480,which allows for controlled positioning of sheath 470 with respect toballoon 424. In some embodiments, a ratchet type system may be includedat proximal end 414 for control of sheath 470 so as to provide morespecific control over distances in incremental stages.

Reference is now made to FIGS. 15A-15D, which are schematicillustrations of the steps of a method of treating a vessel, inaccordance with embodiments of the present invention. A vessel 300having a lesion 302 of length L is accessed via tracking guidewire 49 asshown in FIG. 7A. Tracking guidewire 49 is backloaded onto system 400 byplacing tracking guidewire 49 through distal connecting element 438, andsystem 400 is advanced over tracking guidewire 49 to the vicinity oflesion 302, as shown in FIG. 15B. System 400 may then be pulled backproximally so that tracking guidewire 49 is adjacent balloon 424 and isin a vicinity of lesion 302. Sheath 470 is then pulled back proximally,thereby providing an exposed portion 425 of balloon 424, wherein exposedportion 425 is of a length suitable for treating lesion 302 of length L.The length of exposed portion 425 may be controlled at a proximal end ofsystem 400 using markings 480 as described with respect to FIG. 14.Exposed portion 425 of balloon 424 is then expanded by inflating balloon424, as shown in FIG. 15D. It should be readily apparent that a strengthof sheath 470 prevents portions of balloon 424 within sheath 470 fromalso being expanded. In some embodiments, system 400 may be removed andexchanged with another catheter or catheter system using a rapidexchange method, wherein system 400 is removed proximally along trackingguidewire 49 and the other catheter or catheter system is introducedover tracking guidewire 49.

Although the invention has been described in conjunction with specificembodiments thereof, it is evident that many alternatives, modificationsand variations will be apparent to those skilled in the art.Accordingly, it is intended to embrace all such alternatives,modifications and variations that fall within the spirit and broad scopeof the appended claims. All publications, patents and patentapplications mentioned in this specification are herein incorporated intheir entirety by reference into the specification, to the same extentas if each individual publication, patent or patent application wasspecifically and individually indicated to be incorporated herein byreference. In addition, citation or identification of any reference inthis application shall not be construed as an admission that suchreference is available as prior art to the present invention.

1. A device for introduction into a vessel, comprising: a main elongatedelement having a main elongated element proximal end and a mainelongated element distal end; a balloon positioned at the main elongatedelement distal end, the balloon having a balloon proximal end, a balloondistal end, and an inflation lumen therethrough; a distal connectingelement positioned at the distal end of the balloon to receive aguidewire during use; and a longitudinally movable sheath positionedexternal to the main elongated element, the longitudinally movablesheath having a distal end and a proximal end, wherein a position of thesheath distal end with respect to the balloon defines an exposed portionof the balloon that expands when fluid is delivered to the balloonthrough the inflation lumen.
 2. The device according to claim 1, furthercomprising a tracking guidewire for advancement of the device into thevessel, the tracking guidewire positioned through the distal connectingelement, wherein the distal connecting element is a generallycylindrical rail attached to the balloon distal end.
 3. The deviceaccording to claim 1, further comprising a core wire unslidinglyattached to the main elongated element at a core wire attachment point,the core wire including an internal core wire portion positioned withinthe main elongated element and an external core wire portion positioneddistally with respect to the internal core wire portion, the externalcore wire portion external to and running alongside the balloon.
 4. Thedevice according to claim 3, wherein the distal connecting element is ata rotational distance from the external core wire portion of the corewire.
 5. The device according to claim 3, the device further comprisinga first radiopaque marker and a second radiopaque marker on the corewire along a first longitudinal axis, and a third radiopaque marker on asecond longitudinal axis different from the first longitudinal axis. 6.The device according to claim 3, wherein the external core wire portionfurther comprises a coil wrapped around at least a portion thereof, thecoil-wrapped portion positioned adjacent to the balloon, and at leastone radiopaque marker on the external core wire portion.
 7. The deviceaccording to claim 1, wherein a distal end of the sheath includes atapered end with a soft edge that expands upon retraction of the sheathover the balloon.
 8. The device according to claim 1, wherein the sheathcomprises a braided material to prevent an unexposed portion of theballoon from expanding when the sheath is positioned external to theunexposed portion of the balloon.
 9. The device according to claim 1,wherein the sheath comprises a helical coil to prevent an unexposedportion of the balloon from expanding when the sheath is positionedexternal to the unexposed portion of the balloon.
 10. The deviceaccording to claim 1, further comprising an auxiliary elongate elementproximal to the balloon within a portion of the main elongate elementand aligned with the distal connecting element, and a core wire attachedto the auxiliary elongate element.
 11. The device according to claim 1,further comprising a handle at a proximal end of the sheath forlongitudinally positioning the sheath with respect to the balloon. 12.The device according to claim 11, wherein the handle includes markingsto indicate the sheath retraction and provide a length of the exposedportion of the balloon.
 13. A device for introduction into a vessel,comprising: a main elongated element having a main elongated elementproximal end and a main elongated element distal end; a balloonpositioned at the main elongated element distal end, the balloon havinga balloon proximal end, a balloon distal end, and an inflation lumentherethrough; a core wire including an external core wire portionpositioned external to and running alongside the balloon; a distalconnecting element positioned at the distal end of the balloon toreceive a guidewire during use; and a longitudinally movable sheathpositioned coaxial with the main elongated element, the longitudinallymovable sheath having a distal end and a proximal end, wherein aposition of the distal end of the longitudinally movable sheath withrespect to the balloon defines an exposed portion of the balloon, theexposed portion configured to expand when the inflation lumen is filledwith fluid.
 14. The device according to claim 13, further comprising atracking guidewire for advancement of the device into the vessel, thetracking guidewire positioned through the distal connecting element,wherein the distal connecting element is a tapered rail attached to theballoon distal end.
 15. The device according to claim 13, wherein themain elongated element comprises a flexible portion, the core wirefurther comprising an internal core wire portion positioned along anentire length of the flexible portion, the external core wire portionfurther comprising a radiopaque marker and a coil wrapped around atleast a portion of the external core wire, the coil-wrapped portionpositioned adjacent to the balloon, and wherein the distal connectingelement is at a rotational distance from the external core wire portionof the core wire.
 16. A method for treating a lesion in a vessel,comprising: providing a device having a main elongated element, aballoon positioned at a distal end of the main elongated element, adistal connecting element positioned at a distal end of the balloon, anda longitudinally movable sheath positioned external to the mainelongated element and a portion of the balloon; inserting a trackingguidewire into the vessel; backloading the tracking guidewire into thedistal connecting element; advancing the device over the trackingguidewire until the distal end of the device is adjacent to the lesion;retracting the sheath to expose an exposed portion of the balloon havinga length suitable for treating the lesion; inflating the exposed portionof the balloon to push at least the tracking guidewire against a firstportion of the lesion in the vessel, wherein the sheath preventsexpansion of an unexposed portion of the balloon.
 17. The methodaccording to claim 16, wherein the device further comprises a core wirewith an external core wire portion external to and running alongside theballoon, wherein inflating the exposed portion of the balloon pushes theexternal core wire portion against a second portion of the lesionrotationally displaced from the first portion.
 18. The method accordingto claim 16, wherein the sheath is initially positioned in a most distalposition fully covering the balloon for insertion and comprises atapered tip that expands during retraction of the sheath to expose theexposed portion of the balloon.
 19. The method according to claim 16,wherein retracting the sheath is controlled at a proximal end of thedevice, the proximal end of the device including markings to indicatethe length of the exposed portion of the balloon.
 20. The methodaccording to claim 16, further comprising removing the device proximallyalong the tracking guidewire and exchanging for a second device using arapid exchange method.